Ingredients (U.S. measurements):
4 Large tuna steaks - see note 1
8 tablespoons (1/2 cup) Extra virgin olive oil
Lemon zest from one small lemon (finely chopped)
1 1/2 ounces Capers (finely chopped) - see note 2
1/2 teaspoon French mustard
1 tablespoon Anchovy paste
1 tablespoon Lemon juice
Salt for seasoning